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We generalize the concept of ascending and descending runs from permutations to rooted labelled trees and mappings, i.e., functions from the set $\{1, \dots, n\}$ into itself. A combinatorial decomposition of the corresponding functional…

Combinatorics · Mathematics 2020-07-06 Marie-Louise Lackner , Alois Panholzer

Let $F(x)=\sum\limits_{n=1}^\infty\tau(n)x^n$ be the generating function for the number $\tau(n)$ of spanning trees in the circulant graphs $C_{n}(s_1,s_2,\ldots,s_k).$ We show that $F(x)$ is a rational function with integer coefficients…

Combinatorics · Mathematics 2018-11-12 A. D. Mednykh , I. A. Mednykh

The active bijection forms a package of results studied by the authors in a series of papers in oriented matroids. The present paper is intended to state the main results in the particular case, and more widespread language, of graphs. We…

Combinatorics · Mathematics 2018-07-19 Emeric Gioan , Michel Las Vergnas

We show an $\widetilde{O}(m^{1.5} \epsilon^{-1})$ time algorithm that on a graph with $m$ edges and $n$ vertices outputs its spanning tree count up to a multiplicative $(1+\epsilon)$ factor with high probability, improving on the previous…

Data Structures and Algorithms · Computer Science 2025-05-21 Yang P. Liu , Richard Peng , Junzhao Yang

In this paper, we prove that every $n$-vertex connected $K_{1,5}$-free graph $G$ with $\sigma_4(G)\geq n-1$ contains a spanning tree with at most $5$ leaves and branch vertices in total. Moreover, the degree sum condition "$\sigma_4(G)\geq…

Combinatorics · Mathematics 2022-07-12 Pham Hoang Ha , Nguyen Hoang Trang

Spanning trees are an important quantity characterizing the reliability of a network, however, explicitly determining the number of spanning trees in networks is a theoretical challenge. In this paper, we study the number of spanning trees…

Statistical Mechanics · Physics 2010-08-03 Zhongzhi Zhang , Hongxiao Liu , Bin Wu , Shuigeng Zhou

Let $R$ and $B$ be a set of red points and a set of blue points in the plane, respectively, such that $R\cup B$ is in general position, and let $f:R \to \{2,3,4, \ldots \}$ be a function. We show that if $2\le |B|\le \sum_{x\in R}(f(x)-2) +…

Discrete Mathematics · Computer Science 2018-12-10 Mikio Kano , Kenta Noguchi , David Orden

The graph of overlapping permutations is a directed graph that is an analogue to the De Bruijn graph. It consists of vertices that are permutations of length $n$ and edges that are permutations of length $n+1$ in which an edge $a_1\cdots…

Combinatorics · Mathematics 2016-09-09 John Asplund , N. Bradley Fox

Let $G$ be a connected graph on $n$ vertices and $D(G)$ its distance matrix. The formula for computing the determinant of this matrix in terms of the number of vertices is known when the graph is either a tree or {a} unicyclic graph. In…

We show that for any $\varepsilon>0$ and $\Delta\in\mathbb{N}$, there exists $\alpha>0$ such that for sufficiently large $n$, every $n$-vertex graph $G$ satisfying that $\delta(G)\geq\varepsilon n$ and $e(X, Y)>0$ for every pair of disjoint…

Combinatorics · Mathematics 2023-02-09 Jie Han , Jie Hu , Lidan Ping , Guanghui Wang , Yi Wang , Donglei Yang

The main goal of this article is to introduce new quantitative characteristics of cycles in finite simple connected graphs and to establish relations of these characteristics with the stretch and spanning tree congestion of graphs. The main…

The complexity of a graph is the number of its labeled spanning trees. In this work complexity is studied in settings that admit regular graphs. An exact formula is established linking complexity of the complement of a regular graph to…

Combinatorics · Mathematics 2025-08-18 Gregory P Constantine , Gregory Magda

For a given function from a set to itself, we can define a directed graph called the functional graph, where the vertices are the elements of the set, and the edges are all the pairs of inputs and outputs for the function. In this article…

Combinatorics · Mathematics 2025-09-23 Tadahisa Nara

The status of a vertex $v$ in a connected graph is the sum of the distances from $v$ to all other vertices. The status sequence of a connected graph is the list of the statuses of all the vertices of the graph. In this paper we investigate…

Combinatorics · Mathematics 2020-02-03 Aida Abiad , Boris Brimkov , Alexander Grigoriev

We prove that every amenable one-ended Cayley graph has an invariant spanning tree of one end. More generally, for any 1-ended amenable unimodular random graph we construct a factor of iid percolation (jointly unimodular subgraph) that is…

Probability · Mathematics 2020-05-11 Adam Timar

Let $\alpha(n)$ be the least number $k$ for which there exists a simple graph with $k$ vertices having precisely $n \geq 3$ spanning trees. Similarly, define $\beta(n)$ as the least number $k$ for which there exists a simple graph with $k$…

Combinatorics · Mathematics 2013-02-12 Jernej Azarija , Riste Škrekovski

We study the inertia of distance matrices of weighted graphs. Our novel congruence-based proof of the inertia of weighted trees extends to a proof for the inertia of weighted unicyclic graphs whose cycle is a triangle. Partial results are…

Combinatorics · Mathematics 2023-04-26 Jeffrey Cheng , Ian Malcolm Johnson McInnis , Matthew Yee

Let $D$ be a connected weighted digraph. The relation between the vertex weighted complexity (with a fixed root) of the line digraph of $D$ and the edge weighted complexity (with a fixed root) of $D$ has been given in (L. Levine, Sandpile…

Combinatorics · Mathematics 2021-06-24 Xuemei Chen , Xian'an Jin , Weigen Yan

The main purpose of the paper is to develop an approach to evaluation or estimation of the spanning tree congestion of planar graphs. This approach is used to evaluate the spanning tree congestion of triangular grids.

Combinatorics · Mathematics 2010-09-07 M. I. Ostrovskii

In this paper, we introduce the concept of spanning simplicial complexes $\Delta_s(G)$ associated to a simple finite connected graph G. We give the characterization of all spanning trees of the uni-cyclic graph $U_{n,m}$. In particular, we…

Commutative Algebra · Mathematics 2020-09-25 Imran Anwar , Zahid Raza , Agha Kashif